Can anyone help me ID this???

wmayer92 · Aug 8, 2025

Howdy folks.

New reefer here. My tank has been up and running for about 6 months and I am running into a situation that has me very confused. My tank is being invaded by what looks to be colorless zoas type corals? I included some photos to show you what I'm seeing. They are starting to pop up all over my rock, all over my substrate, and even on my algea scrubber. It looks like they have no plans of stopping anytime soon as I'm seeing upwards of 75+ with new ones sprouting everyday.

I tried to grab them with my finger when I was doing water changes at the start, but they retract immediately upon being touched and I can't grab them... I tried to gravel vac the ones on the substrate with no luck as well. They just shrink every time.

I had one small zoa colony around the two month mark once I jumped into some beginner corals. For some reason (I'm sure I'm just learning and getting used to things) the zoa's never really did very well. I moved them a couple of times for different lighting/flow and was never able to see them prosper. Eventually they started to grow upwards, lose color, and looked like the things in my photos. I figured they weren't doing well, and wanted to take them out and try my luck again. A week or two after I took out the plug they were attached to, these things started to pop up on my rocks.

What in the world are these? Is there a way I can stop them from spreading? Am I being invaded by the ghosts of my distressed zoa's? Or is this something else entirely?

I am quite confused and looking for any and all help, I'm eager to learn. Thanks!

(Also, I chose the zoa page because that's what they looked like, let me know if I need to move this post elsewhere)

bluemon · Aug 8, 2025

Aiptasia.

One of the worst pests.

Probably came in with the zoas and stung them to death.

They are anemone that will reproduce like crazy given the chance.

At this point, it seems like it’s on a path where you cant do manual removal by killing them individually as they are popping out from the sand.

Maybe try a biological control like peppermints or berghia?

JohnNYC8 · Aug 8, 2025

wmayer92 said:
Howdy folks.

New reefer here. My tank has been up and running for about 6 months and I am running into a situation that has me very confused. My tank is being invaded by what looks to be colorless zoas type corals? I included some photos to show you what I'm seeing. They are starting to pop up all over my rock, all over my substrate, and even on my algea scrubber. It looks like they have no plans of stopping anytime soon as I'm seeing upwards of 75+ with new ones sprouting everyday.

I tried to grab them with my finger when I was doing water changes at the start, but they retract immediately upon being touched and I can't grab them... I tried to gravel vac the ones on the substrate with no luck as well. They just shrink every time.

I had one small zoa colony around the two month mark once I jumped into some beginner corals. For some reason (I'm sure I'm just learning and getting used to things) the zoa's never really did very well. I moved them a couple of times for different lighting/flow and was never able to see them prosper. Eventually they started to grow upwards, lose color, and looked like the things in my photos. I figured they weren't doing well, and wanted to take them out and try my luck again. A week or two after I took out the plug they were attached to, these things started to pop up on my rocks.

What in the world are these? Is there a way I can stop them from spreading? Am I being invaded by the ghosts of my distressed zoa's? Or is this something else entirely?

I am quite confused and looking for any and all help, I'm eager to learn. Thanks!

(Also, I chose the zoa page because that's what they looked like, let me know if I need to move this post elsewhere)

It’s aiptasia and it’s unfortunately very common. I wouldn’t panic, most reef tanks deal with the issue and get it under control. When they’re disturbed they release eggs and multiply. If you have 75+ each day you’ll need some tank inhabitant to help with control.

Do you have space (30-40+ gallons) for an aiptasia eating filefish? They can nip at corals but are aiptasia’s worst nightmare. There are also other fish who eat aiptaisa: https://reefbuilders.com/2024/08/14/five-fish-that-will-eat-aiptasia-nuisance-anemones/

Berghia nudibranchs will definitely work but they’re expensive and they’ll probably die off before the aiptasia is eradicated (if aiptasia can ever really be eradicated). You need to add at least 3 berghia so they have a chance to multiply and take out the aiptasia. Peppermint shrimp should keep them in check once you clear out the big numbers. But make sure you get peppermints who are aiptasia eaters if you go this route.